In 2G to 4G mobile communications systems, a cell is generally divided into three sectors or six sectors according to a hexagon, where each sector performs communications service transmission by using a broadcast beam or a narrow beam. The broadcast beam is generally a wide beam covering a whole sector, and is used to transmit a control signal, a voice signal, and the like at a low data rate. The narrow beam is used to perform transmission at a high data rate. In the 2G to 4G mobile communications systems, an antenna is an omni-directional antenna or a directional antenna, and a fixed zero-filling wide coverage beam or a narrow beam moving in a sector is used.
For adapting to new requirements that mobile communication continuously raises for a data rate, a high frequency, high bandwidth, multiple antennas, and multi-cell division become a development trend of new-generation mobile communication.
Some prior art provides a multi-antenna beam coverage system applied to cellular communication and broadcasting. In this technology, a system antenna divides sectors according to 120 degrees, where three antenna beams exist in each sector. The three antenna beams include two broadcast beams (a multi-cell omni-directional coverage beam and a single-cell specific broadcast beam) and one narrow beam (a sectoral beam whose direction can be adjusted in a cell). In this technology, the system includes multiple antennas, a signal allocation network, and a control circuit. This technology uses a multi-carrier multi-antenna system, which is used to form the three antenna beams. Three antenna units include an omni-directional antenna, a directional wide beam antenna, and a narrow beam antenna with an adjustable directivity pattern, and the antenna units need to be independently designed according to different beam characteristics. The signal allocation network allocates multiple input signals to a corresponding antenna unit. In this technology, the narrow beam needs to scan in a whole sector, and multi-user same-type data shares one narrow beam, causing a service capacity of a communications system to be limited.